The steroid hormone, estradiol (E2), synthesized by and secreted from the ovaries is an accurate index of the time of ovulation in mammals. The ability to accurately predict the time of ovulation greatly enhances the efficiency and, therefore, profitability of commercial breeding farms. Currently, veterinarians and breeding farm managers must submit samples to a diagnostic laboratory to determine estradiol concentrations. This process is expensive, inefficient and requires elaborate detection systems. The studies proposed are designed to develop and validate a rapid, on-site colorimetric test for the determination of estradiol levels in biological fluids. The on-site test will be designed in such a way to yield a three stage color development where low E2 concentrations will result in an intense color change, moderate E2 concentrations will result in modest, but discernable, color change and high E2 concentrations will produce no color change. Two approaches for the assay, namely a solid-phase and a liquid phase, will be tested. Each approach will utilize several substrates to determine that substrate which yields the most distinguishable changes in color in parallel to changes in E2 concentrations. Development and commercialization of an on-side test to predict "breeding readiness" has immediate applications to the horse industry. Furthermore, after establishment of the equine market, modification of the kit for application to other species is envisioned. PROPOSED COMMERCIAL APPLICATIONS: First application will be in the $25.3 billion horse industry. The ability to accurately predict ovulation will greatly enhance efficiency and maximize the market potential of breeding farms. Modification of the test for use in other species, including humans, will further enhance its market value.